1. Field of the Invention
The present invention relates to method for wrapping electrical cables for storage. In particular, the present invention relates to a device and method of wrapping an electrical cable to minimize the 60 Hz alternating current impedance of a stored electric cable.
2. Discussion of Background
Electric utility employees generally ground their vehicles when they are working in close proximity to an energized electric power line. Grounding is especially important for vehicles that have lift attachments, to lift workers and equipment above the ground to service power lines and transformers.
Vehicular grounding is accomplished using a heavy number 2 AWG gauge or larger copper cable stored on a reel on the back, side or front of the vehicle. One end of the cable is permanently attached to the frame of the vehicle; the other end has a heavy clamp that can be attached to a suitable earth ground, such as the closest utility pole ground, a temporary ground rod driven into the ground, or the system neutral. Because suitable earth grounds are not always close to the vehicle, the grounding cable is typically provided in lengths of about 70 feet or more. However, the length of the cable itself presents two safety problems.
The coiled cable is potentially a huge inductor. If a worker reels off only a portion of the cable, enough to reach the nearest earth ground, and part of the truck comes into contact with the line, the worker is in danger of exposure to electric shock from the voltage induced in the partially coiled cable. This voltage is as much as two or three times higher than what would occur if the cable were completely uncoiled from its storage reel and laid on the ground.
To minimize the impact of a partially coiled cable serving as an inductor, utility companies often require that the cable be completely uncoiled and placed on the ground. However, in the event a high level of fault current is passed through an unsecured cable lying on the ground, it can whip violently and injure workers from the physical impact.
Thus, although necessary to prevent even greater injury from an ungrounded vehicle, the grounding cable is itself a source of injury.